Project GD STI- Keeping Cool with Greddy and Koyo!


We hooked up the Synapse DV to apply vacuum in the pull direction to both top substrates.  This is the second fastest reacting way to set the valve up.  We had previously tried the DV in the push direction with just the inner substrate hooked up, the fastest reacting set up and found that it had super fast response which would be good for drag racing at it allows for the least boost loss during shifts.  However this was too sensitive and made the car have a jumpy response to throttle modulation when in turns and at light throttle. This upset the chassis balance and made things a bit scary when cornering on the edge.  When we slowed the valve down a little, the car was much more settled in cornering.  The DV's tuneabilty has proven to be a very useful setup tool for optimizing the system.
The stock front bumper brace is a substantial strong and stiff piece so we were worried about the front end's structural integrity in a crash.  We were also worried that we might have really changed things like air bag deployment calibration and stuff.  We think that the big brace tying the frame rails together is also a key element of chassis stiffness in torsion.  Because of this we had Brian weld up two chromoly thinwall 1.25″ tubes to tie the ends of the bumper support stiffly.  Brian reinforced the bars with two dimple die gussets which still allows some airflow to the intercooler core.  Now we once again had a decent degree of front end protection and stiffness.
The tubular brace butts up against the inside of the bumper cover giving it more support while still allowing the IC core some breathing room.  Since the cut out section of bumper brace also weighs a ton, our modded bumper saves a lot of weight.  The new parts of the bumper were rattle canned black for corrosion resistance.
Once again we paid a visit to the AWD dyno of Cobb So Cal.  Our first pulls with the new stuff proved to be disappointing.  We had less power than stock, more lag and less throttle response.  However this is typical with a larger intercooler install with no other changes.  Our A/F ratio was on the lean side as Subies are very sensitive to intake/MAF changes.  The lag and throttle response issues were due to the larger intercooler internal volume and the long intercooler pipes feeding the engine.
Cobb's ace tuner Mitch Mckee modifies the maps to optimize the engine's tune for the intercooler.  He richened up the air fuel ratio and fixed the low end boost curve and then added some more timing and a little more top end boost as the car had a zero knock count even though it was a hundred degree day thanks to the much improved intercooling.  The tuning woke the car up even though the changes in the tune were slight.
The results of tuning?  A gain of 23 hp and 22 lb/ft of torque with power gains across the board!  Turbo lag was improved over stock due to the improved intercooling allowing more timing and boost in this part of the powerband, spooling the turbo faster.  The only negative was a very slight decrease in transient throttle response due to the increase of intake tract volume from the longer tubes and bigger intercooler.  This was very minimal and to complain about it would be very nitpicking as some people might not even notice it. Time for more mods!  Look at the power curve.  That nice, wide and flat useable power is awesome!

So far we have gotten good gains and have laid down a good base for more power.  Our knock count is zero, our coolant temp hovers at the thermostat opening point even with our unusually hot summer and full blast AC use and we have more than doubled our oil cooling capacity for when we hit the track.

Stay tuned, next we will test out a Cobb downpipe and high flow cat and will improve our fuel delivery.  We also have more suspension and brake improvements coming,

Read more about Project GD STI here!


Koyo Cooling Systems

Cobb Tuning

Cobb Tuning So Cal

Afterhours Automotive


KW Suspension

Mackin Industries Advan Wheels

Falken Tires

West End Alignment



PLX Devices - Kiwi Bluetooth

Palmer DashCommand

3M Window Films (Renewable Energy Division)

Frank Garrido – Owner
Tint Factory Solar Concepts Inc – 3M Authorized Dealer
2033 South La Cienega Blvd.
Los Angeles, CA 90034


  1. Do you have any other picture for where the cooler mounts. Im trying to install the same kit on a 2004 sti and have trouble figuring out where the lower bracket goes.


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